Hydrogen storage properties of modified fumed-Fe-dust generated from a revolving furnace at a steel industry

Pure hydrogen can be chemically stored and supplied directly to PEFC via the redox of modified fumed-Fe-dust obtained from steel company: storage of H2:Fe3O4+4H2→3Fe+4H2OH2:Fe3O4+4H2→3Fe+4H2O or Fe2O3(initialstate)+3H2→2Fe+3H2O; recovery of H2:3Fe+4H2O→Fe3O4+4H2H2:3Fe+4H2O→Fe3O4+4H2. Modified fumed-Fe-dust with various metal additives has been prepared by impregnating metal cations of Cr, Al, Zr, Mo, Mo–Al, Mo–Ti, Mo–Zr, Mo–Ce, Mo–Rh, Mo–Ni or Mo–Cu. The reduction of the oxidized fumed-Fe-dust (denoted as FeOxFeOx) with and without additives and the performances of formation H2 of the reduced FeOxFeOx-dust have been mainly investigated. The results show that: (1) among the metal additives tested, Mo was the most effective element to enhance the rate of H2 produced in the oxidation with H2O as well as cyclic stability in repeated redox cycles for oxidized fumed-Fe-dust at low temperature 354 °C; (2) the state of additive Mo in oxidized FeOxFeOx was suggested to be the chemical composition of 2FeO·MoO22FeO·MoO2 based on the result of XRD spectra; (3) the sintering of the particles was one of the factors effecting on the catalytic activity and cycling stability of the modified FeOxFeOx, but what kinds of metal additives to be added in FeOxFeOx must be much more important for the sample to promote catalytic activity and keep cyclic stability effective.